v1:http://www.newgrounds.com/dump/item/50ee6940c366d79de36167391c899309

v2:http://www.newgrounds.com/dump/item/c5f84238ebfc01a2795652f93ef32fee

v3:http://www.newgrounds.com/dump/item/f7e8b6b91d0bfe6c6293fce693665bed

v4:http://www.newgrounds.com/dump/item/e10dab4ed989f568d642f41dd33836ac

changes:
V3

- Fixed the undefined char in the 2nd lvl.

- Added many new things in shop, including chaingun.

- Added a G03LM you can hire in shop called The Butcher.

- Increased basic G03LM stats and changed char to lvl 5.
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V4

- Made every character in the entire game playable.

- Unlocked every level so you don't have to play through.

- Made zombies friendly when you are one of them.

- Added a few items in the shop.

- Added a new guy in shop.

have fun

http://www.newgrounds.com/dump/item/93b5c254cad3e333fe45336f32c42dc4 a new sprite sheet created with flash pro cs6